Abstract
Introduction Cannabis use disorders (CUD) are highly prevalent among patients with schizophrenia
(SCZ). Deficient mismatch negativity (MMN) generation is a characteristic finding
in SCZ patients and cannabis users. This study therefore examined the effects of CUD
on MMN generation in SCZ patients.
Methods Twenty SCZ − CUD patients, 21 SCZ+CUD patients, and 20 healthy controls (HC) were
included in this study. MMN to frequency and duration deviants was elicited within
an auditory oddball paradigm and recorded by 32 channel EEG.
Results As expected, SCZ − CUD patients showed reduced frontocentral MMN amplitudes to duration
deviants compared to HC. Interestingly, SCZ+CUD patients demonstrated greater MMN
amplitudes to duration deviants compared to SCZ − CUD patients at central electrodes
with no differences compared to HC.
Discussion These results demonstrate that comorbid cannabis use in SCZ patients might be associated
with superior cognitive functioning. It can be assumed that the association between
cannabis use and better cognitive performance may be due to a subgroup of cognitively
less impaired SCZ patients characterized by lower genetic vulnerability for psychosis.
Key words
cannabis - mismatch negativity - event-related potentials - schizophrenia - comorbidity